so i was reading the threads about ppl choosing the 4-1 over the 4-2-1 and i cant find who has actual numbers to prove it. i saw these for shorts on ebay headers and whats your opinion for a 2.2L auto ? its got a full cai and dtm muffler i want something to help increase sound and performance mostly for street speeds not too worrried about high rpm performance as its bascially a d/d